Raukawa

Raukaua edgerleyi

At Risk - Declining

This native plant, known as Raukawa (scientific name: Raukaua edgerleyi), is a remarkable species endemic to New Zealand. It is characterized by its unique features, ecological role, and cultural significance. This comprehensive guide provides detailed information on its care, propagation, and importance within the New Zealand ecosystem. Understanding this plant contributes to the appreciation of our rich biodiversity and heritage, and supports conservation efforts for Native Trees.

Raukawa (Raukaua edgerleyi) showing its glossy, aromatic leaves — Image credit: Raukawa (*Raukaua edgerleyi*) - photo by Wikipedia

Plant Description

Raukaua edgerleyi, commonly known as Raukawa, is an elegant evergreen tree reaching heights of up to 12 metres. It is particularly noted for its glossy, dark green foliage that emits a pleasant aromatic scent when crushed. A striking feature of this tree is its heterophylly, where juvenile and adult leaves differ significantly. Juvenile leaves are compound with 3 to 5 deeply lobed leaflets, while adult leaves are simple, elliptical, and smooth-edged. The bark is smooth and pale grey, becoming rougher with age. Small greenish flowers appear in spring, followed by dark purple fleshy fruits that are highly attractive to native birds.

Quick Facts

*Raukaua edgerleyi* quick facts
Scientific Name	Raukaua edgerleyi
Height	10-12 metres
Spread	4-6 metres
Water Needs	Moderate
Light	Full sun to partial shade
Frost Tolerance	Tolerant of light frost
Salt Tolerance	Moderate
Growth Rate	Moderate
Lifespan	Long-lived

Climate Best Suited to

Raukawa is found throughout the North, South, and Stewart Islands, adapting well to a range of temperate climates. It prefers areas with consistent rainfall and is often found in lowland to montane forest environments. While it can handle coastal conditions and wind, it thrives best in positions that offer some protection from extreme exposure.

Regional Suitability

City suitability for Raukawa
City	Climate Suitability
Auckland	Excellent
Wellington	Excellent
Christchurch	Good
Dunedin	Good
Hamilton	Excellent
Tauranga	Excellent

Plant Habitat

Raukawa naturally inhabits lowland to montane forests, often occurring as a scattered but important component of the subcanopy. It is frequently associated with podocarp-broadleaf forests, where it benefits from the humid, sheltered conditions provided by larger canopy trees. It grows well in fertile, well-draining soils rich in organic matter, typical of uninterrupted forest floors.

Plant Conservation

Currently classified as 'At Risk - Declining', Raukaua edgerleyi faces significant threats from introduced mammalian browsers. Possums, deer, and goats find the foliage highly palatable and can cause severe damage or death to both young and established trees. Habitat fragmentation also poses a long-term risk to its natural distribution.

Growing Requirements

Soil Requirements

Fertile and Well-drained

Requires moisture-retentive but free-draining soil.
Benefits from high organic content (compost or leaf mold).
Avoids heavy, waterlogged clays.

Light Requirements

Sun to Partial Shade

Tolerates full sun if roots are kept cool and moist.
Prefers filtered light or partial shade in hotter climates.
Grows well in forest understory conditions.

Water Requirements

Regular Moisture

Requires regular watering during the first few growing seasons.
Does not tolerate prolonged drought well.
Mulching is essential to maintain consistent root moisture.

Planting Guide

When planting Raukawa, choose a sheltered spot that mimics its natural forest habitat. The ideal time for planting is during the autumn or early spring when the soil is moist and temperatures are mild. Prepare the site by incorporating plenty of organic matter into the soil. Dig a hole twice the width of the root ball and ensure the tree is planted at the same depth as it was in its container. Water thoroughly after planting and apply a thick layer of organic mulch around the base, keeping it clear of the trunk to prevent rot.

Ecological Role

Raukawa plays a vital role in New Zealand's forest biodiversity. Its aromatic flowers attract a variety of native insects, including bees and moths, which serve as pollinators. The fleshy purple fruits are a significant food source for native birds such as the Kererū, Tūī, and Bellbird. In turn, these birds facilitate the dispersal of seeds throughout the forest, supporting the regeneration of the species.

Uses & Significance

Garden Uses

Ornamental and Aromatic

Excellent specimen tree for native and aromatic gardens.
Provides attractive textural contrast with its juvenile foliage.
Supports native bird life in urban environments.

Ecological Value

Biodiversity Support

Important food source for frugivorous native birds.
Contributes to the health of podocarp-broadleaf forest ecosystems.
Valuable for ecological restoration and revegetation projects.

Cultural Significance

Raukawa holds deep cultural importance for Māori. The tree is celebrated for its highly aromatic leaves, from which a fragrant oil was traditionally extracted to create perfumes. These leaves were also used to scent other oils or rubbed directly on the skin. The significance of this plant is perhaps most visible in the naming of the Ngāti Raukawa iwi, who trace their name back to this prized forest tree.

Aromatic leaves were used by Māori to create perfumes.
Ngāti Raukawa tribe was named in honour of this tree.
Symbol of forest fragrance and cultural heritage.

Landscaping Uses

In landscaping, Raukawa is valued for its tidy growth habit and the sensory appeal of its scented leaves. It works well as a specimen tree in medium to large gardens or as part of a sheltered native border. Its ability to support native wildlife makes it a popular choice for gardeners looking to enhance local biodiversity. It can also be used effectively in restoration plantings aimed at recreating authentic lowland forest communities.

Seasonal Care Calendar

Spring

Flowering and Growth

Monitor for new growth flushes.
Observe small greenish flowers.
Ensure adequate moisture as temperatures rise.

Summer

Fruit Development

Water regularly during dry spells.
Maintain thick mulch layer to keep roots cool.
Protect from high-intensity direct sun if possible.

Autumn

Fruiting and Planting

Collect ripe purple fruits for seed propagation.
Ideal time for planting new specimens.
Clean up any fallen debris around the base.

Winter

Dormancy

Protect young trees from heavy frosts.
Inspect for signs of pest browsing (possums/deer).
Prune any dead or damaged wood.

When to Prune and How Much

Raukawa generally requires very little pruning, as it naturally develops a pleasing and tidy form.

Best pruned in late winter or early spring before new growth begins.
Limit pruning to the removal of dead, diseased, or crossing branches.
Avoid heavy pruning, as the tree responds best to minimal intervention.

Light formative pruning can be done on young trees to encourage a strong central leader and balanced canopy, but this is often unnecessary if the tree is well-sited.

How to Grow Raukawa (Raukaua edgerleyi)

From Seed

Propagating Raukawa (Raukaua edgerleyi) from seed is a rewarding process that requires careful handling and timing. The journey begins in late summer or autumn when the tree's fleshy fruits turn from green to a deep, dark purple. It is crucial to harvest the berries directly from the tree or immediately after they fall to ensure maximum viability. Once collected, the fleshy outer pulp must be removed, as it contains natural inhibitors that prevent germination. This can be achieved by soaking the berries in water for 24 hours and then gently rubbing them against a fine sieve.

After cleaning, the seeds should be sown immediately into a high-quality, well-draining seed-raising mix. Do not store the seeds, as they are highly perishable and lose viability rapidly if allowed to dry out. Lightly cover the seeds with a thin layer of the mix or fine vermiculite. Place the seed tray in a warm, sheltered spot away from direct sunlight, and ensure the medium remains consistently moist but not waterlogged. Germination is typically slow and irregular, often taking several months. Once the seedlings have developed their first few sets of leaves, they can be carefully transplanted into individual pots.

From Cuttings

For those who prefer vegetative propagation, Raukawa can also be grown from semi-hardwood cuttings. This method is often preferred for maintaining the characteristics of a specific parent tree. The best time to take cuttings is in late summer or autumn, using healthy, vigorous growth that has started to firm up but is not yet fully woody.

Select cuttings approximately 10-15 cm long, making a clean cut just below a node.
Remove the lower leaves and dip the base of the cutting into a rooting hormone powder or gel to stimulate root development.
Insert the cuttings into a well-draining propagation mix, such as a blend of peat and perlite.
Maintain a humid environment by covering the pots with a clear plastic bag or placing them in a misting unit.
Keep the cuttings in a bright but shaded position and ensure they never dry out. Rooting can be slow, often taking several months.

Additional Methods

Layering and Natural Regeneration

While seed and cuttings are the primary methods, layering can occasionally be successful with lower branches. However, the most effective way to see new Raukawa in your area is to protect existing trees from browsing pests, allowing natural regeneration through bird-dispersed seeds to take place within the forest ecosystem.

Pests & Diseases

The most formidable threat to Raukaua edgerleyi is browsing by introduced mammalian pests. Possums are particularly fond of the succulent, aromatic leaves and can quickly defoliate a tree. Protection through trapping or exclusion fencing is vital. While generally robust, the tree can occasionally be affected by leaf spots or scale insects if grown in poorly ventilated or overly stressed conditions.

Bonus Tip

To enjoy the famous fragrance of Raukawa, gently crush a leaf between your fingers. The release of aromatic oils provides a sensory connection to the traditional perfumes of Aotearoa. This practice is a simple way to identify the tree in the wild and appreciate its historical significance.